Not applicable.
A mounting for a mirror is known from U.S. Pat. No. 5,781,355 and German Patent Document DE 296 03 024 U1. This mounting has a baseplate that is connected to a mirror support via an compensating structure. This compensating structure is a filigree structure with hinges which are articulated with middle portions by means of rods, the baseplate and the support plate being connected to the same by means of rods arranged perpendicularly to the compensating structures arranged parallel to the baseplate and support plate. The compensating structures are preferably of aluminum and compensate the different thermal expansions of the baseplate and support plate by elastic deformation.
A device for play-free vertical displacement of objects is known from German Patent Document DE 32 46 358 A1. This device has plates that are arranged approximately mutually parallel, and are respectively connected to each other by a monolithic hinge. Furthermore, the second and third plates are provided with a respective screw passing through the plate and are supported on the respective underlying plate. The respective plate is supported on the underlying plate by the respective screw and the monolithic hinge. A desired tilt angle of the respective plate can be set by rotation of the screw. A notch is provided in the uppermost plate to receive the object to be displaced.
The invention relates to an optical bench according to the preamble of claim 1. An optical bench which has a baseplate is known from European Patent Document EP 844 473 A1. This baseplate is provided with seatings which are connected to associated optical units. The axes of the optical units are mutually parallel and perpendicular to the baseplate of the optical bench.
It is disadvantageous in this optical bench that due to the perpendicular arrangement of the axes of the optical units to the baseplate, this bench structure takes up a great deal of space. It is furthermore disadvantageous that stresses arise due to temperature fluctuations or due to a temperature gradient arising in the baseplate, due to the adjacent arrangement of seatings and baseplate, so that the deformations resulting from the stresses are transmitted to the adjacently arranged seatings.
Furthermore, the invention had as its object to provide an optical bench which is of compact construction.
Furthermore, the invention had as its object to provide an optical bench in which the effect of thermal fluctuations on the relative arrangement of the optical units to one another is prevented.
The object of the invention is attained by means of the features given in claim 1. By means of the measure of providing an optical bench with a baseplate which has a seating which can be arranged, by means of associated connecting elements, with respect to the baseplate, movable in its entirety relatively to the same, in which stresses arising in the baseplate are not transmitted, or are transmitted at least only in a slight degree, to the seatings. The stresses are transformed into a deformation of the baseplate relative to the seating. These stresses thereby do not act on the seating, so that the relative arrangement of the optical units mounted on the seating does not change.
It has been found to be advantageous to provide the relative deformation of the seating element and the baseplate by means of connecting elements which preferably comprise springs. As springs, leaf springs have been found to be particularly suitable.
However, connecting elements which include articulations could also be provided. These articulations are to permit a movement of the baseplate relative to the seating only by the action of a predetermined minimum force, so that the transmission of vibrations from the baseplate to the seating is prevented.
It has been found to be advantageous to provide as the seating, a monolithic member which is constituted with inner bores for beam guiding. High shape stability and a homogeneous temperature distribution are attainable by the use of a monolithic member.
Furthermore, it has been found to be advantageous to provide for the seating a housing-like hollow member with apertures for the coupling-on of optical units. The weight can be reduced by the provision of a housing-like hollow member as the seating. The use of a multi-part housing-like seating can also have an advantageous effect as regards production costs, particularly material costs, since the seating is thus not to be produced from a massive block of material.
It has been found to be advantageous that the seating has a material which has a high ratio of thermal conductivity to thermal expansion coefficient. The formation of a temperature gradient in the receiver, which could result in stresses and a deformation of the seating, is opposed by a high thermal conductivity. The changes in dimensions resulting from temperature fluctuations are small because of a small thermal expansion coefficient, so that the relative arrangement of the optical units connected to the seating changes little, if at all. Deformations due to a temperature gradient often cause a distortion of the respective component. A loss of the initially existing parallelism results from a distortion and can have serious effects on an optical system. In particular, a distortion of the seating is particularly critical for this reason.
A ceramic material, preferably Zerodur, has been found to be particularly advantageous for the seating. With a compact constitution of the seating, the seating can be resistant against launching loads because of its dimensions, so that a ceramic can be used as the material for the seating, ensuring an acceptable life of the seating.
It has been found to be advantageous to make the baseplate at least partially of a metal, in order to be able to ensure a resistance to high launching loads, if the use of the optical bench in a satellite system is planned. In particular, the greater dimensions of the baseplate as compared with the seating demand greater stability because of this effective launching load.
It has been found to be advantageous to make the baseplate triangular with a centrally arranged perforation and flange segments, so that the baseplate can be securely connected to an associated component by means of the flange segments; in particular, the optical bench can be secured by means of the flange segments to the optical head of an associated satellite. The constitution of the baseplate in a triangular shape is advantageous in reducing its own weight.
It has been found to be advantageous to constitute the baseplate for the formation of a mounting structure with reinforcements, which are preferably in the form of ribs, the baseplate having support points for coupling a telescope to it. Such a mounting structure can be constituted in one piece, particularly of aluminum for weight reduction.
To ensure a uniform temperature distribution within the seating, the connecting elements have a cross section which is predetermined in dependence on its thermal conductivity, to provide a predetermined thermal coupling between the baseplate and seating. When the seating is heated on one side, a heat accumulation is opposed by the slight removal of heat over the connecting elements, and the formation of a temperature gradient is opposed due to the high thermal conductivity of the material of the seating.
It has been found to be advantageous to provide in addition a heat conducting strip which serves to remove heat to prevent overheating, particularly of the optical elements, at least at a temperature of the seating exceeding a predetermined temperature threshold.
It has been found to be advantageous to connect the receiving unit and the transmitting unit securely to the seating, so that these two optical elements, reacting sensitively to relative position changes, are mounted by means of the seating and are thus decoupled from deformations of the baseplate.
It has been found to be advantageous to provide the baseplate with a connection for an optical unit, preferably with mounting points for the seating of a deflecting mirror. By a deflecting mirror, which is preferably adjustable for the adjustment of the incident beam, direction changes of the same can be compensated. Thus the deflecting mirror can be mounted on a component which undergoes large deformations due to temperature fluctuations. Further advantageous measures are described in further dependent claims. The invention is described in detail hereinafter using an embodiment example.